Categorised by physical & chemical properties & by relative atomic mass
1 of 18
1817
Döbereiner grouped similar elements called triads
2 of 18
1863
Newlands arranged it by mass. Came up with law of octaves
3 of 18
1869
Mendeleev arranged atoms by mass but left gaps
4 of 18
Modern Periodic Table
Moseley in 1914. Arranged elements by increasing atomic (proton) number
5 of 18
Nuclear Charge
The more protons , the more positively charged & stronger the attract for electrons
6 of 18
Atomic Radius
Attraction falls off very rapidly with distance. An electron close to the nucleus will be much more strongly attracted than one further away
7 of 18
Shielding
As the number of electrons between the outer electrons & the nucleus increases the outer electrons feel less attraction towards the nuclear charge.Lessening the pull of the nucleus by inner shell electrons
8 of 18
IE Down a Group
Decreases as its easier to lose electrons
9 of 18
IE Across a Period
Increases as its harder to lose electrons
10 of 18
Reactivity Increases Down Group 2
Due to increasing atomic radius & shielding affect
11 of 18
Group 2 Element + Water
Forms a metal hydroxide and hydrogen
12 of 18
Group 2 Element + Oxygen
Forms a solid white oxide
13 of 18
Group 2 Element + Dilute Acid
Forms a salt & hydrogen
14 of 18
Test For Carbonates
Add dilute acid. If present the carbon dioxide will be released, then do limewater test
15 of 18
Test For Sulfates
Add dilute HCl, then barium chloride solution. If positive a white precipitate is formed
16 of 18
Test For Halides
Add nitric acid, then silver nitrate solution. White precipitate if silver chloride, cream precipitate if silver bromide & yellow precipitate if silver iodine
17 of 18
Test For Ammonium Compounds
Add sodium hydroxide & warm mixture. Use damp red litmus paper if positive it will turn blue
Comments
No comments have yet been made